Tone control system for controlling a remote station



Sept. 6, 1955 w. B. BRUENE 2,717,371

TONE CONTROL SYSTEM FOR CONTROLLING A REMOTE STATION Filed Aug. 9, 1951 TRANJMITTER Po WER 6 TAT! ON INVENTOR. WARRE/v 5. BRUENE BY /y A ToRn/Ey United States Patent TONE CONTROL SYSTEM FOR CONTROLLING A REMOTE STATION Warren B. Bruene, Cedar Rapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application August 9, 1951, Serial No. 241,100 3 Claims. (Cl. 340-170) This invention relates in general to a control system and in particular to means for selectively operating a pair of relays or other controlled apparatus remotely.

It is oftentimes desirable to control from a remote position, a transmitter or receiver. For example, oftentimes a radio transmitter may be located a number of miles from its control station. It is. desirable to be able to turn the transmitter on remotely and in some cases, change frequencies or perform other operations from the remote control station.

It is an object of this invention therefore, to provide means for remotely controlling apparatus.

Another object of this invention is to provide means for remotely controlling either of a pair of relays.

Yet another object of this invention is to provide means for selectively operating one of two relays.

A feature of this invention is found in. the provision for a phase comparison circuit which uses a reference voltage of the same phase at the remote and controlled stations so as to selectively operate either one of two relays.

Further objects, features and advantages of this invention will become apparent from the following description and claims when read in view of the drawing, in which;

The single figure illustrates schematically the remote control apparatus of this invention.

A control station is provided at which a dial 10, as for example, a telephone dial, is connected in series with 'a resistor R1 and one side 14 of a transformer 11 which has its mid-point grounded. The primary 12 of the transformer is connected to a suitable power supply, as for example, 60 cycle, 110 volts, which might come from some centrally located power station 13. A resistor R2 is connected to the other side of the secondary .14 and a switch S1 is connected to resistor R2 and to the other side of dial 10. p

The dial 10 is connected to one winding Lrof a transformer 16. A microphone 17 is connected to an inductance L2 which forms a second winding of a transformer 16. A third winding of the transformer 16, L3, is connected to a pair ofwires 18 and 19 which join the control station with the controlled station.

The opposite ends of .wires 18 and 19 are connected to a winding L; of a transformer 21. The secondary L of transformer 21 has its midpoint grounded and opposite. ends connected to the grids 22, 23, 24 and 26 of tubesvi, V2, V3 and V4.

.The cathodes 27 and 28 of tubes V1 and V3 are connected together and in series with a resistor R3 to ground. The cathodes 29 and 31. of tubes V2 and V4 are connected together and to ground through a resistor R4. The plate 32 of tube V1 is connected to one end of a winding L6 of a transformer 33. The opposite side of winding L6 is connected to the plate 34 of tube V:'. g

- Plate 36 of tube V2 is connected to a second winding L7 of transformer 33. The opposite end of winding L7 is connected to the plate 37 of tube V4. The mid-point of winding L6 is connected to a relay 38 which has its opposite side connected tozground. Therelay 38 when 2,717,37i Patented Sept. 6, 1955 energized closes a switch 8;; which is connected to ground and has its open side connected to a transmitter 39.

Likewise, winding L r has its mid-point connected to a relay 41 which has its opposite side'connected to ground. The relay 41 actuates a switch S3 which has its open side connected to the transmitter 39. A third winding Ls of the transformer 33 is connected to the power station'13.

The transmitter 39 is connected to a suitable antenna 42. A filter 43 is located at the controlled station and removes the voice from the wires 18 and 19-and supplies I it to the transmitter 39 for modulation.

In operation, let it be assumed that it is desired to tune the transmitter 39 to a particular frequency and to transmit voice modulation after it is tuned. The dial l o has ten or more positions of which nine might. correspond; to a particular frequency for the transmitter.

One of the positions might turn on the filament heaters of the electron tubes of the transmitter to prepare it for transmission. If the dial is actuated and released, a signal will be coupled through the transformers 16 and 21 to the grids of tubes V1,- V2, V3 and V4. The tones transmitted by the telephone dial 10 causes tubes .V1 and V3 to conduct for the reason that the power furnished by the power station 13 to the windings 12 and La are in phase and thus tubes V1 and'Va have their plates and grids in phase and they will therefore conduct. r

The voltage on the plates and grids of V2 and V4 are 180 degrees out of phase and there will be no conduction.

When tubes V1 and V3 conduct, the relay 38 will be energized, thus closing switch S2 and the. control information from the telephone dial 10 will be furnished to the transmitter 39. For example, the telephone dial 10 might transmit a number of pulses corresponding to the number dialed. This will cause the switch S2 to close the same number of times asrthe number dialed and the transmitter 39 will have a stepping switch or other tone resolver which can interpret the signal. A- stepping switch 50 suitable for use with the transmitter is illustrated in the single figure and is connected between the relay actuated switch S2 and the transmitter 39. v The operation and circuitry involved in the stepping switch is as follows: Actuation of the dial 10 to the stop position is effective to close the circuit from the secondary terminal of transformer 11 through resistor R1, the. dial switch 10 and the transformer primary L1 .to ground. This energizes the grids 22 and 24 of the tubes V1 and V3 respectively with a voltage of the same phase as that ap..- plied to the corresponding plates. Accordingly, conduction in these tubes results and relay 38 is energized and switch S2 is actuated to the closed position. I

Closure of switch S2 is effective to energize the release relay 51 of the, stepping switch 50.. This circuit is com,- pleted from ground atswitch S2 through the contacts of switch S2, the normally closed contact 59, the winding of relay 51 to the positive terminal of the battery 71 and back to ground 72. Actuation of ,the relay 51 mechanically drives the selector ,brush 53 to the home position through a mechanical linkage 52 represented. by the dashed line. The closure of switch S2 is also effective to energize slow release relay 60 and to open the normally closed contact 61. Opening of contract 61 interrupts the circuit connection between the selector switch brush 53 and the transmitter 39 for a time interval suflicient to permit the stepping switch to come to rest at the position selected.

When the stepping switch brush 53 is driven to its home position by the linkage 52, the brush engages the contact blade 54 and displaces this blade into engagement with the contact 55. Closure of the contact blade 54 and contact 55 is effective to complete a circuit through stepping relay 56 and slow release relay 58 from the ground connection at switch S2 to the positive terminal of the battery 71 and thence to the ground connection 72. Energization of slow release relay 58 actuates the normally closed contact 59 from its upper position to engagement with the lower contact. This actuation of switch 59 interrupt's the circuit of the release relay 51 to prevent this relay from driving the selector switch. brush tothe home position upon the occurrence of succeeding pulses. A closure of the contact arm 59 against the lower contact also provides a circuit connection directly from switch S2 through stepping relay 56 to the positive terminal of the battery 71, for actuation by succeeding pulses.

Upon the release of the dial 10 at its stop position, it will return to its normal position andproduce a number of pulses corresponding to the number dialed. Release of the dial interrupts the first pulse. This interruption permits relay 38 to open switch S2, thus tie-energizing stepping relay 56. De-energization of relay 56 releases the relay armature which is connected to the steppi -22: switch brush 53 through the linkage 63 represented by the dashed line. Release of the relay armature thus causes the stepping switch brush 53 to advance by one position. In the same. manner, each succeeding pulse produced at the control station will cause the stepping switch brush 53 to advance one position until the position corresponding to the number dialed has been reached. At this point, slow release relay 60. will permit normally closed contact 61 to return to its closed position tocomplete the circuit from the selected one of the circuits 62 through the stepping relay brush 53 and normally closed contact 61 to the transmitter 39. The circuit 62 selected by the stepping switch brush corr'espondsto a particular frequency to which the transmitter is thereby tuned.

Assume that the transmitter 39 has been prepared for transmission by the dial 10 and its related circuitry. The

switch. S1 may then be closed, thus causing tubesVz and V4 to conduct, thus energizing relay 41 which closes switch S3. The switch S3 might be. the transmitter on position or push-to-talk switch to put the transmitter on the air. Closure of the switch S3 by relay 41 is effective to connect the high voltage power supply 74 to the transmitter 39. The circuit is completed fromthe ground connection at switch S3 through the closed contact of switch S3, the winding of relay 70, and the battery 71 to the ground connection 72. Energization of relay 7t closes the contact 73, which is effective to energize the high voltage power supply. When the high voltage power supply is thus energized, the high voltage output is supplied between the ground connection 75 and the input terminal of transmitter 39. p

The modulation may be furnished over the microphone 17 through the wires 18 and 19. and to the transmitter through the filter 43. v

In order for this apparatus to work, it is necessary that the windings 12 of transformer 11 and L of transformer 33 be energized with the same phase power supply. One of the main advantages of this system is its simplicity and saving of wires. It is to be noted that only two wires 18 and 19 need to be connected between the controlled and the control station. 7

This invention provides a very simple means of selecs tively operating a pair of control relays at a remote point over a single pair of lines which might. be, for example, telephone or telegraph lines that may also carry audio for voice communication. This is called a tone control system but the tone used is the power line frequency.

The two-phase detectors are the heart of this invention. They comprise, respectively, the tubes V1, V3, and V2, V4. When the 60 cycle tone applied to the telephone line causes the grid of the tubes V1- and V3 to be in phase with the alternating voltage on their plates, they will conduct on the positive half cycles, thus rectifying the alternating current to operate the pulsing relay 38. If the phase of the applied tone is reversed by 180, then the right pair of tubes V2 and V4 will conduct instead and the relay 41 will be operated.

The main advantage of this circuit over conventional systems is its simplicity. The usual tone oscillators, selective filters, amplifiers, rectifiers and associated direct current power supplies, are replaced by the simple circuit which is operated entirely by alternating power.

The system utilizes the fact. that normally 60 cycle power supply is available over a relatively large area from the same power supply For example, the lines 18 and 19 might be rented telephone lines and the phase detecting system of this invention allows two wires to be eliminated between the control." and the controlIed station. This is a substantial saving in maintenance. and rent of telephone or other lines.

Althoughthis invention has been described with respect to particular embodiments thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention as defined by the appended claims.

l. A tone control system for controlling, a controlled station from a remote position comprising, a powerst'ation supplying power to the control and the controlled stations, a first transformer located at the control. sta tion with its primary connected to the power station, the secondary of said first transformer having its. midpoint connected to ground, first and'second switching means connected to opposite sides ofithe secondary of the first transformer, a second transformer located at the control station, a primary of the second transformer connected to the first and second switching; means, a. pair of communication lines connected -to the secondary of said second transformer and extending from the control to the controlled stations, a third transformer Iocatedrat the controlled station with its primary connected to the pair of communication lines, the midpoint of the. sec ondary of the third transformer connected to ground, two pairs of electron tubes. at the. controlled station the control grids of the first pair of electron. tubes connected to one side of the secondary'of said third trans.-

former, the control grids of. the second pair. of electron tubes connected to the opposite side of the secondaryof the third transformer, a fourth transformer locatedat the controlled station and having its primary connected to the power station, a. first secondary of the. fourth transformer with one end connected to the plateof one. of the first pair of electron tubes, and the: opposite endconnected to the plate of one. of the second pair of electron tubes, a second secondary of said fourth transformer with one end connected. to the plate of the other of said first pair of electron tubes. and the oppositeend connected to the plate of the other of said second pair of electron tubes, a first relay connected between ground and the mid-point of the first secondary of the said fourth transformer, a second relay connected between ground and the mid-point of the second secondary of said fourth transformer, and. the said first and. second. relays furnishing control signals.

2. A tone control system for controlling. a remote station comprising, a controlstation having a first trans former with its primary energized by a tone voltage source. and provided with a secondary winding having a center tap connected to ground, a. second transformer atsaid control station having a grounded. primary winding.

means for energizing said second, transformer with a tone voltage of selectable phase including. a first switch. means adapted to: connect the primary winding ofifsdl'd second transformer to. one terminal of said secondar y winding, a second switch means adapted to. connectthe said primary winding of said. second transformer-.- tovthe other terminal of said secondary winding, means for en age and said signal voltage at said controlled station and having a pair of input terminals connected across said lines, a pair of signal voltage output terminals and a pair of tone voltage output terminals, a signal voltage utilization device at said controlled station, means connecting said signal voltage output terminals to said device, means for controlling said device in response to actuation of said switch means including means connecting said tone voltage output terminals across the primary winding of a third transformer, two pairs of electron tubes, the control grids of each pair connected to different terminals of the secondary winding of said third transformer, the cathodes of the first pair of electron tubes connected together, the cathodes of the second pair of electron tubes connected together, a fourth transformer with its primary energized from said tone voltage source, first and second secondary windings on the fourth transformer with the said first secondary windings having its opposite ends connected to the plates of the first pair of electron tubes, the said second secondary winding having its opposite ends connected to the plates of the second pair of electron tubes, a first control relay connected between ground and the midpoint of the said first secondary winding and a second control relay connected between the midpoint of the said second secondary winding and ground.

3. In combination a control station, a controlled station, a pair of communication lines between said stations, an alternating voltage source common to said stations, phase responsive means at said controlled station including first and second selectively conductive electron tubes and first and second selectively actuated relays, each of said tubes being provided with plate and grid electrodes and being rendered conductive for actuating the corresponding one of said relays when both of said electrodes are energized with voltages of the same phase, one of said electrodes of one tube energized from said source with a voltage of one phase, one of said electrodes of the other tube energized from said source with a voltage of the opposite phase, the others of said electrodes of each tube being coupled to said pair of lines, a transformer at said control station energized from said source and having a secondary Winding with a grounded center tap, a first selector switch at said control station connected between one terminal of said secondary winding and a grounded transformer coupling to said line for energizing the said line with a voltage of one phase, and a second selector switch at said control station connected between the other terminal of said secondary winding and a grounded transformer coupling to said line for energizing said line with a voltage of the opposite phase, the first of said selector switches being of the dial actuated type having intermittently actuated contacts for producing a selectable number of pulses, and a stepping switch in driven connection with said first selectively actuated relay at said controlled station.

References Cited in the file of this patent UNITED STATES PATENTS 1,928,093 Coyle Sept. 26, 1933 2,100,467 Borden Nov. 30, 1937 2,285,815 Holden June 9, 1942 2,349,987 Place May 30, 1944 2,378,326 Rees et al June 12, 1945 2,384,336 Pfieger Sept. 4, 1945 2,427,850 Gehman Sept. 23, 1947 FOREIGN PATENTS 132,453 Austria Mar. 25, 1933 

